The Siemens 7KT1664 is the MID-certified M-Bus variant of the PAC1600 series for CT-connected 5 A measurement. It is the go-to choice for multi-tenant commercial buildings where M-Bus networks carry billing-grade energy data from tenant sub-meters fed through current transformers at the main distribution level.

Why M-Bus + CT-connected + MID — what application does this combination serve?

This is the classic multi-tenant sub-metering configuration. The CT input allows measurement of large loads — hundreds or thousands of amps — through appropriately sized current transformers, while the meter itself stays compact on a DIN rail in the metering cabinet. M-Bus networks all tenant meters back to a central collection point without the wiring complexity of individual RS-485 runs. MID certification makes each meter's readings legally valid for tenant invoicing. Together, these three features serve exactly the use case of a commercial building with multiple tenants, each metered at the main distribution board through CTs.

How do I select the right current transformers for the 7KT1664?

The meter accepts standard /5 A secondary current transformers. Select CTs with a primary rating at least equal to the maximum expected load current — common choices are 100/5, 200/5, 400/5, or 600/5 A. The CT must have a rated burden of at least 2.5 VA (the meter's input burden is minimal at roughly 0.3 VA per phase) and an accuracy class appropriate for the application (Class 0.5 or Class 1 CTs for billing). MID compliance requires that the complete measuring chain — CTs plus meter — meets the overall accuracy requirements.

Frequently Asked Questions

Can I use the 7KT1664 on a single-phase supply?

The 7KT1664 is a three-phase meter and expects all three phase voltages for correct operation and MID-compliant measurement. For single-phase applications with M-Bus and MID, Siemens offers the PAC1600 single-phase range (7KT165x series).

Does MID certification affect how I install and seal the meter?

MID-certified meters must be installed in accordance with local legal metrology regulations, which typically require sealing of the terminal cover and CT connections to prevent tampering. The meter itself is factory-sealed. Ensure the CT secondary wiring is also protected against unauthorized access to maintain the legal validity of the measurements.